1. The supporting pipeline of the GRI-9003 Trace Oxygen Analyzer should be sealed. Small leaks will allow oxygen in the ambient air to diffuse in, resulting in high measurement values.

Although in the measurement, the sample pressure is greater than the ambient pressure, but the oxygen in the sample gas is a trace, according to the Ferrari law, the partial pressure of oxygen is proportional to its volume content, the atmosphere contains about 21% of oxygen, and with PPM The oxygen partial pressure of the calculated sample gas is about 10,000 times different. Therefore, the partial pressure of trace oxygen in the sample gas is much lower than the oxygen partial pressure in the atmosphere. When a leak occurs, oxygen in the atmosphere will rapidly diffuse from the leaked part. Come in.

Also, the sampling line should be as short as possible, and the number of joints should be as small as possible to ensure that the joints and valves are well sealed. After the pipelines are connected, a tightness check should be done.

Requirements for air tightness inspection: Under 0.25MPAm test pressure, 30 minutes, the pressure drop is not more than 0.01 MPA.

2. The material of the pipeline is basically brass or stainless steel pipe, and the PTFE pipe is the second choice. Forbidden tubes such as latex tubes and white rubber tubes have poor gas-tightness and material permeability resistance, and the measurement of trace oxygen is too inaccurate under the standard measurement pressure. The outer diameter of the pipeline is usually 6mm or 1/4IN, and 3mm or 1/8IN is also preferred. In short, the stainless steel tube is preferred for cleaning and degreasing to keep the inner wall of the tube smooth and clean. For trace level (<1PPMV) oxygen analysis, Stainless steel tubes polished on the inner wall should be selected. For valves and fittings selected, the dead volume should be as small as possible.

3. In order to prevent the condensation of moisture in the sample on the pipe wall, resulting in the dissolution and absorption of trace oxygen, the sampling pipeline shall be subjected to thermal insulation or heat insulation measures according to the situation. When detecting trace amounts of oxygen in liquid nitrogen, special attention should be paid to heating measures. Otherwise, because the oxygen boiling point is lower than the nitrogen boiling point of 13 degrees, the sample gas will not be gasified uniformly, which will result in a seriously low measurement value.

4. In principle, the measurement position of the trace oxygen analyzer should be as close to the measurement unit as possible to avoid excessively long pipelines and excessive uncertainties, affecting the reliability of the measurement data.

5, the sample gas can not contain oil components or solid particles, so as to avoid blocking and pollution of the osmotic membrane.

6. The sample gas should not contain sulfides, phosphides or acid gas components. These components can cause damage to fuel cells, especially alkaline fuel cells.